B204 oil pressure drops

This problem is driving me insane! Initially the car, 1999 SAAB 9-3 convertible FSP/HOT (T5, 200HP engine, stage 0), had initially a intermittent blinking oil pressure light. This should be fixable, i thought. Well that seems to be for the untrained eye. After the initial problem with the original engine the problem as resurfaced again even when the engine has been replaced.

Original problem:

  • Oil light intermittent while idling.
  • Balance chain cut by the SAAB dealer (chain links found in the sump)

First diagnosed and tried to fix the problem on the original block:

  • Pulled the sump of the car
  • Cleaned the clogged oil pickup strainer
  • Replaced oil filter (genuine GM, partnr. 55560202)
  • Replaced oil (genuine GM, partnr. 93165557, full synthetic 5W30)
  • Replaced oil switch (partnr. 9112459 )

Driven for 2000 km without a oil pressure light lighting up (anxiously keeping an eye on it) and all of a sudden the oil pressure light came on. Directly pulled the car over to the shoulder and called a tow-truck for expedition.


  • main and rod bearings totally worn
  • found ‘copper flakes’ in sump
  • crankshaft bent

So i decided the replace the bottom part of the engine.

Engine replaced and overhauled:

  • Sourced a B204 turbo engine (bottom part with crankshaft and pistons)
  • Thermostat kit, genuine GM, partnr. 30577561
  • Cylinder head bolts, genuine GM, partnr. 5955794
  • Front oil seal crank, genuine GM, partnr. 55557231
  • Rear oil seal crank, genuine GM, partnr. 55557240
  • Gasket cylinder head, genuine GM, partnr. 9185695
  • Gasket exhaust manifold, genuine GM, partnr. 55557285
  • Valve stem seals, genuine GM, partnr. 5955570
  • Timing and balance kit, genuine GM, partnr. 93184480
  • Turbo charger full fitting kit, alternative, partnr. 21349999
  • Exhaust manifold repair kit, alternative, partnr. 21347280
  • Timing cover, genuine GM, partnr. 9542622 (used but in good condition)
  • Pressure relief valve spring, genuine GM, partnr. 9309998
  • Pressure relief valve, genuine GM, partnr. 9167784
  • Replaced the timing cover
  • Replaced the oil pump gears
  • Replaced the oil pickup seal
  • Replaced the oil transfer pipe seals
  • Replaced the pump cover seal
  • Flushed and cleaned the oil cooler
  • Replaced oil cooler seals
  • Replaced oil filter (multiple times already)
  • Exchanged oil thermostat

Not replaced

  • Cilinder head, before fitting the head has been milled to make it straight flattened again.
  • Turbo, Garret T25
  • Oil cooler (flushed and blasted clean with 8 bar air) 
  • Oil filter housing

As the – timing and balancing kit – didn’t include the correct sprockets for the balance rods i decided to leave the chain off, left the rods in the engine and placed a blanking plate under the balance chain tensioner to avoid possible oil leakage.

Mounted everything together and measured, using a mechanical pressure gauge, to see if the pressure was stable. After running the engine to a normal operational temperature everything seemed fine. While running idle the oil pressure measured ±2.1 bar.

Argghhhh, not again!

Took the car for a test drive. After 15 minuten, engine heated up again to normal values and at the traffic light i noticed that the oil light was flickering again. However when touching the gas pedal for just a little bit the light went off.

So the while idling the oil pressure dropped from the idle ±2.1 bar to a minimal low point at ± 0.55 bar but did rise again while revving the engine. So seems as the visocity changes the problem arises.

As i have added a sandwhich plate between the engine and the oilfilter, i can read the values from the Equus oil pressure gauge, which ranges from 0 to 7 bar.

Got the engine back into the garage again.

Now what? Now i am completely lost at this point.



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